Grinding machine



A. H. BALL.

GRINDNG MACHINE Dec. 23, 1952 2 SHEETSSHEET 1 Filed June 15, 1951 INVENTOR.

ZILBERT h, BALL 14 TTORNE Y8.

Dec. 23, 1952 A. H. DALL GRINDING MACHINE 2 Sl-lEETS-Sl-IEET 2 Filed June 15, 1951 70 ill]? 1 TTORNEYS.

Patented Dec. 23, 1952 GRINDING MACHINE Albert H, Dall, Cincinnati, Ohio, assignor to The Cincinnati Milling Machine 0.0., Cincinnati, Ohio, a corporation of Ohio.

Application June 15, 1951,. SerialNo..231,778

20- Claims. 1

This. invention. relates: to improvements in grinding machines and: has particular reference to. improved mechanism for accurate control. of the relative traversing movement of the work piece and grinding member.

One of the objects of the present invention is the provision of an improved form of. reversing mechanism particularly adapted for use in connection with roll grinding or like machines having an extended range of traverse movement.

A further object of. the invention is the provision of an improved amplified rate trip mechanisnr for effecting controlled movement ofv a reversing trip or the. like at a rate: in. excess of thexrate of. movement of the controlled part for increasing the sensitivity and accuracy of. trip operation.

Another 'obj ect: of the invention is. the provision of an improved accurate trip control. mechanisnr for roll grinders or the like positionable adjacent the operator's station whereby accurate adjustment. may be. readilyeflected and the control mechanism will be accessible and at all times under observation of the operator for checking of accuracy of setting and permissible manual supplemental control as desired.

Other objects and advantages of the present invention should be readily apparent by reference to the. following specification, considered in conjunction with the accompanying drawings forming apart thereof, andit-is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Figure 1. is a cross sectional view of a roll grinding machine embodying the present invention.

Figure 2. is an enlarged fragmentary view of the control elements partially in elevation and partially broken away.

Figure3 is a vertical sectional view on the line 3-3 of Figure 2.

Figure 4 is a, horizontal sectional view on the line 44 of Figure 2.

Figure 5 is a fragmentary view partially in section illustrating the interengagement of the respective trip dogs with the abutment portion of the trip-lever, and

Figure 6 is a view partially in section of the proj'ectable trip dog.

The present invention is particularly desirable for use in connection with large r011 grinding machines designed for the production or resurfacingof the necksandbodies ofstraight, concavev or convex hotand cold. plate mill rolls, sheet and tin mill. rolls, and the. like of the type. illustrated, for example, in Letters Patent, 2,170,494 to'Ernst et a1. Reference is, therefore, made to this patent as showing the general structural features ofsuch a machinev whichin themselves form no essential part of the present invention. Such commercially known machinesv are fre quentlyof size tov handlework pieces from three to five feet in diameter and 20 feet or more in length. From the type of work to be produced by such rolls, it is essential that the grinding be extremely accurate and the final surface produced. to an extremely high standard of perfection free from chatter from grinding lines or the like. In finish grinding of the roll periphery it is important that the relative traverse of wheel and work is. so controlled that. the wheel does not, overrun the edge of the work and that the point of the various reversals be accurate and consistent. If. the wheel overruns the roll when the surface being finished projects radially beyond: the roll neck, or alternatively, when grinding up to:a terminal shoulder, if the wheel overruns apart of the roll, however small, which is not being finished, a roughing of the wheel is liable to result which will produce a feed line on the work on the return stroke. Once produced, such a feed line or other imperfection resulting from grinding on the roll surface is difficult to remove and since the corrective grinding must be carried, out throughthe entire length of the work. piece greatly increases the time. of production, while if the reversal is frequently appreciably variable or inconsistent, the required highly accurate finish may neverbe obtained.

It has been found that rolls of this type can best be commercially produced on what is termed a traveling wheel head type of grinder, and the invention has therefore. been illustrated as so utilized, although it will be understood that the rinciples of the invention may be utilized with the drive taken from a traveling work table or support in place of being coupled, as shown, with the wheel head drive mechanism.

In the drawing the numeral 10 designates a suitable frame or supportv for the grinding machine elements having mounted on the left hand portion thereof the rails H and I2, providing ways l3 and M for the work supporting and driving means such as the headstock [5.

On the right hand side there has been shown in depressed or lower relation with respect to the rails I1 and I2 the second set of rails l6 and I! supporting the V-way l8 and flat way 19 for the wheel head carriage 20 of the type shown, for example, at in Letters Patent 2,170,494. As shown in said patent, the carriage is designed to be reciprocated longitudinally of the machine by means of a pinion 2| carried by the driven shaft 22 and meshing with rack 23 carried by the frame 24 intervening the rails l6 and I1.

For effecting rotation of the shaft 22 for traversing the wheel head the shaft has keyed thereon the drive worm gear 25 meshing with the driven worm 26 corresponding to worm 83 of the Ernst et a1. patent, coupled with a drive motor 55.

In carrying out the present invention, shaft 22 is provided with an upwardly extending portion 2? journaled in the column 23 rigidly mounted on and movable with the wheelhead carriage 2c. The column 28 has an enlarged head 29 receiving the bevel drive gear 30 on the upper end of shaft extension 21. This bevel gear meshes with a second bevel gear 3| secured on the stub shaft 32 journaled in the housing plate 33 secured to the face of column 28. A compound gear 34 having a portion 35 of one diameter and a second adjacent portion 36 of slightly reduced diameter is secured on the forward end of shaft 32 for rotation therewith. These gears have similar teeth, but due to the difference in diameter there is a difference in the total number of such teeth, which may be in desired ratio, the particular structure shown being designed with '7 3 teeth on the gear 35 and '72 teeth on the gear 36.

Mounted on the plate 33 is a face plate or housing 31 having journaled therein at opposite sides the sleeves 38 and 39. At its inner end the sleeve 33 carries a gear id meshing with the gear 35 and having, for example, 34 teeth, while journaled within the sleeve 38 is a shaft 4i bearing a gear 62 meshing with the gear 35 and having, for example, 33 teeth. The sleeve 38 is pro vided on its forward end overlying the face plate 31 with a dog disc 43 while the shaft 4| extends through the disc 43 and carries a juxtapositioned second dog disc 44. These parts are particularly shown in detail at the left of Figure 4 where it will be noted that the frame plate 31 is provided with the forwardly extending bearing lugs 45 and 45 for the sleeves 38 and 39. These lugs have exterior bearings t! on which are pivotally mounted the control members or trip levers 48 and d9 retained in position by the end plates 50. The levers are therefore mounted for oscillatory movement with respect to the supporting plate 3? about the axes of the control discs, an interposed spring 5! connecting the upper portions of the respective levers swinging the left hand lever in a clockwise and the right hand lever in a counterclockwise direction to the extent of movement permitted by the abutment lugs 52 on the face of the member 37. The con trol levers are thus resiliently maintained in the normal or non-effective position illustrated in Figure 2 for outward yielding movement of their upper ends. Outward movement of the upper end of the lever 48 serves to actuate switch arm 53 of the motor control switch 54 which has been diagrammatically illustrated as coupled with the table drive motor 55. Correspondingly, outward movement of the upper end of the lever 49 serves to actuate arm '58 of the control switch 5?, likewise diagrammatically illustrated as coupled to motor 55. The switches 54 and 51 may be of standard commercial type and may constitute either stop switches or reversing switches 4 dependent on the particular control desired as respects the drive motor 55.

It will be evident that inward movement of the lower end of either the lever 48 or the lever 69 will actuate the associated switch arm 53 or 55, which movement may at any time be manually effected, or alternately, is eifectable by the action of the combined dogs or trip or abutment devices carried by the associated control discs. In either event, upon release of the lower end of the trip lever either by backing off of the trip dog mechanism or by manual release of the lever, spring 51 will restore whichever lever may have been actuated to its neutral or switch arm releasing position, it being understood that the switches 5-; and El are of standard limit switch type of construction in which the switch arms may be swung upwardly for operation of the switches, but are normally spring reset into the positions shown in Figure 2.

Fcr dog effected operation, each of the switch arms 43 and 2-9 is provided with a flange or bracket portion 58 to which is pivoted at 59 the stop or abutment member 60 having a dog engaging shoulder 6|. .The member 60 is upwardly urged with respect to the bracket by a spring 62 to the extent limited by the stud 63, while a pin or handle as facilitates retraction of the shoulder 6! out of the path of movement of the trip dogs on the discs. It will be noted inthe mechanism shown that the members 66 on the respective levers correspond in structure but are oppositely disposed so that the shoulder 61 effectively opposes the operative directional movement of the trip control mechanisms, but can be oammed downward by reverse movement of the dogs.

For cooperation with the members the discs 46 are provided with the annular T slots at 65 to receive T head bolts 86 adjustably securing in position the dogs 61 having the convex abutment portions fit. These abutment portions are positioned to engage with the transversely extending actuating pins 69 carried by the trip dogs Hi pivoted at "H to the dog elements 12, which are adjustably secured by bolts 13 engageable in T slots M to the discs 43. By this construction the members ill can be adjustably locked in any desired position peripherally of the members 434. The springs operating against the rear of the trip dogs as particularly illus trated in Figure 6 normally hold the dogs inward in a position when rotated to clear the shoulders St on the trip lever abutments 6B. This is the condition which exists except in those instances, such as illustrated in Figure 5, for example, when the member 63 of a dog on disc 44 is brought into registry with a pin 69 on the member iii. Under these conditions, the action of the tapered member 58 in moving into this registering position will cam or force pin 69 and thus the member l0 outwardly so that the tip or shoulder it will be projected to engage and interlock with the shoulder 3! on the member 59.

When the dogs are so positioned, continued rotational movement of the discs will carry with them the associate end of the lever 43 or 49 as the case may be to the extent necessary to actuate its associated switch arm 53 or 56. In the ordinary operation of the machine actuation of the switch will effect a reversal of the drive means resulting in a backing off or reverse actuation of the controlling discs and their, dogs, releasing the actuated lever which is then restored to its initial' position by spring- 5|.

In-the embodiment here illustrated, the relationship between the drive pinion 2| and the gears and Si is such that one revolution of the stub shaft 32 is eiiected for approximately 33 of longitudinal or work traversing movement of the wheel head. or carriagew, while the gear relationshipsand. the diameter of the discs 43' are such thatduring suchtraversing move-- menta point on the periphery of the disc and consequently a trip dog secured at this point will have traveled during this single revolution a distance of 64 or at the ratio of two to one as respects the distance moved by the traversing member of the machine.

It will be understood that by varying the gear ratios, such as 39.-3l, the diameters and number of teeth on the members 36 and it or by varying thev diameter of the discs 43. that this ratio may be either increased. or decreased. It is preferable, however, that the periphery of the discs carrying the control dogs or trips move at a more rapid rate than the rate of movement of the traversing element of the machine controlled.

thereby in the interests of attaining increased sensitivity of response.

It Willbe further noted that by the particular ratio between the teeth on the members 36 and 4042 that while the two controlled discs 43 and 44 have been shown as coupled to be driven in a given direction, they are likewise actuated at difierent or differential rates.

In the particular example given for purposes of understanding of, the invention: the excess movement of the disc 44 with. respect to disc 43 is of the nature of 16 /2 degrees per revolution, or, in. other words, the actuating dog at moves at a rateapproximately one-twentieth second fasterthan the rate of movement. of the interference dog. If the dogs are set inline to eifect actuation of the trip lever 33, as indicated in Figure 5, after one revolution of the disc 43 they will be out of line 16 /2 degrees so; that. the member- H! is completely released; after two revolutions the separation will be 33 degrees and increased by corresponding increments for each revolution. Thus, it is possible for the dog carrying'discs to receive 22 revolutions from an initial setting position beforethey will be lined up again asshown in Figure 5 in a. position to actuate the reversing mechanism. Each, revolution of the disc 43 corresponds to approximately 1.6% inches of traverse movement of the machine element. Utilizing even a small 10" diameter disc, the rate of advance of the tripping dogs will be twice the rate of movement of the. controlled element, thus increasing the accuracy and sensitivity of the tripping operation.

The position ofv the dog carrying discs and associated parts at the operators station enables the operator continuously to observe and, if desired, manually to control or prevent the trip operation. By utilization of the present invention, an extreme range of movement of the wheel carriage'can be readily controlled as to stopping or reversing conditions with a relatively small positively operating control mechanism.

What is claimed is:

1. Control means for a grinding machine or the like having a drive member, and a driven driving said. control members at different relative operation of the drive member,

rates, a 'proj'ectable tripv on one of said control members, a control abutment on the other of said control members, said trip and abutment having interengageable portions efiective on relative movement of the members to project the trip into operative position, and means operable by said trip when projected to determine the operation of the drive member.

2. Control means for a grinding machine or the like having a drive member and a driven member, said control means including a pair of control members, different ratio gearing operated by the drive member for simultaneously driving said control members at different relative. rates, a projectable trip on one of said control members, a control abutment on the other of said control members, said trip and abutment having interengageable portions effective on relative movement of the members to project the. trip into operative position, and means operable by said trip when projected to determine the operation of the drive member, said means including a trip aotuable. switch element.

3'. Control means for a grinding machine or -.tl1e like having a drive member and a driven member, said control means including. a pair of control members, different ratio gearing operated by the drive member for simultaneously driving said control members at different relative rates, a projectable trip onv one of said control members, a control abutmenton the other of said control members, said trip and abutment 1 having interengageable portions efiective on relative movement of. the members to project the trip into operative position, and means operable by said trip when projected to determine the operation of the drive member,v said means including a control lever having a portion extending. into the path. of movement or; the; trip for engagement thereby.

4. Control means for a grinding machine or the like having a drive member and a driven member, said control means including a pair of control members, different ratio gearing operated, by the drive member for simultaneously driving said control members at different relative rates, a projectable trip on one of said control members, a control abutment on the other of said control members, said trip and abutment having interengageable portions effective on relative movement of the members to project the trip into operative position, and means operable by said trip when projected to determine the said means including a switch element coupled with the drive member, and. a switch operating lever having a first portion for engagement with the switch element, and an additional portion extending into the path of movement of the projected trip for actuation thereby.

5. Control means for a grinding machine ineluding a translatable element and a feed mechanism including a rotatable shaft for effecting translation of the element, said control means including gearing driven by said rotatable shaft, a pair of dog carriers actuable by said gearing in synchronism with the, movement of the translatabie element, a projectable dog mounted on one of said carriers, an actuating dog mounted on the other of said carriers and engageable with the prcjectable dog for moving the same into efiective position, a trip device having an actuable portion engageable by the dog when inprojected position, and means operable by the trip 7 device for controlling the movement of the translatable member.

6. Control means for a grinding machine including a translatable element and a feed mechanism including a rotatable shaft for elf-acting translation of the element, said control means including gearing driven by said rotatable shaft, a pair of dog carriers actuable by said gearing in synchronism with the movement of the trans latable element, a proj ectable dog mounted on one of said carriers, an actuating dog mounted on the other of said carriers and engageable with the projectable dog for moving the same into effective position, a trip device having an actuable portion engageable by the dog when in projected position, means operable by the trip device for controlling the movement of the translatable member, and means for retracting the actuable portion of the trip device out of the path of movement of the projected dog.

7. A control mechanism for the translatable member of a grinding machine having a driven shaft for effecting translation of the member and a driver for actuating the shaft, said control mechanism including a master driver, a pair of control discs disposed in juxtaposition one to the other and driven at differential rates by said master driver, a displaceable control dog carried by one of the discs and an actuating dog carried by the other of said discs, said dogs having interengageable portions for effecting displacement of one dog by the other when the dogs are aligned by said differential movement.

8. A control mechanism for the translatable member of a machine having a driven shaft for effecting translation of the member and a driver for driving the shaft, said control mechanism including a master driver, independent pairs of control discs coupled with the driver for actuation thereby, said coupling including gearing for driving one disc of each pair at a selected rate, and additional gearing for driving the other disc of each pair at a different rate, a displaceable control dog carried by one disc of each pair and an abutment dog carried by the other disc of each pair, the dogs of each pair of discs having interengageable portions for eifecting displacement of the dog of one disc by the dog of the other when the respective dogs are aligned by the differential rate of movement of their respective discs, a trip member individual to each pair of discs having an abutment portion engageable by a displaced control dog, switches actuable by said trip members, and connections between said switches and the shaft actuating driver for determining the opera- 1 tion of said driver.

9. A machine of the character described including a support, a carriage movable on the support, drive means for moving the carriage a shaft mounted on the carriage, means for rotating the shaft in synchronism with the rate and extent of movement of the carriage, a control device for the movement of the carriage operable by said shaft including a duplex master gear having distinct gear portions of different diameters, and a trip control unit actuable by said gear, said unit including a first disc having a pinion portion meshing with one diameter of the master control gear and a second concentrically mounted disc having an individual drive pinion meshing with the portion of other diameter of the master control gear whereby said discs may be simultaneously correspondingly rotated at differential rates.

10. A machine of the character described including a support, a carriage movable on the support, drive means for moving the carriage a shaft mounted on the carriage, means for rotating the shaft in synchronism with the rate and extent of movement of the carriage, a control device for the movement of the carriage operable by said shaft including a duplex master gear having distinct gear portions of different diameters, and a trip control unit actuable by said gear, said unit including a first disc having a pinion portion meshing with one diameter of the master control gear and a second concentrically mounted disc having an individual drive pinion meshing with the portion of other diameter of the master control gear whereby said discs may be simultaneously correspondingly rotated at differential rates, each of said discs being formed with relieved attachment receiving portions.

11. A machine of the character described including a support, a carriage movable on the support, drive means for moving the carriage a shaft mounted on the carriage, means for rotating the shaft in synchrcnism with the rate and extent of movement of the carriage, a control device for the movement of the carriage operable by said shaft including a duplex master gear having distinct gear portions of different diameters, a trip control unit actuable by said gear, said unit including a first disc having a pinion portion meshing with one diameter of the master control gear and a second concentrically mounted disc having an individual drive pinion meshing with the portion of other diameter of the master control gear Whereby said discs may be simultaneously correspondingly rotated at difierential rates, each of said discs being formed with relieved attachment re ceiving portions, dogs individual to the respective discs, and means engaged in the relieved attachment receiving portions of the discs adjustably securing the dogs in position on the discs.

12. A machine of the character described including a support, a carriage movable on the support, drive means for moving the carriage a shaft mounted on the carriage, means for rotating the shaft in synchronism with the rate and extent of movement of the carriage, a control device for the movement of the carriage operable by said shaft including a duplex master gear having distinct gear portions of different diameters, a trip control unit actuable by said gear, said unit including a first disc having a pinion portion meshing with one diameter of the master control gear and a second concentrically mounted disc having an individual drive pinion meshing with the portion of other diameter of the master control gear whereby said discs may be simultaneously correspondingly rotated at differential rates, each of said discs being formed with relieved attachment receiving portions, dogs individual to the respective discs, means engaged in the relieved attachment receiving portions of the discs adjustably securing the dogs in position on the discs, a trip member carried by the machine having an abutment disposed in juxtaposition to but out of the normal path of movement of the individual dogs on the discs, and cooperating means on the respective dogs for effecting movement of one of the dogs out of said normal path into a position to engage said abutment when the respective dogs and the abutment means are moved by the differential rates of actuation of the discs into aligned position.

13. A control mechanism for the movable carriage of a machine tool which has a shaft rotatable in synchronism with the movement of the carriage, said control mechanism including a support mounted on the carriage, a master gear journaled in the support having a pa-ir of drive portions of unequal diameter, driving connections between said shaft and the gear, a pair of sleeves journaled in the support, each having a pinion portion meshing with a portion of the gear of one diameter, a control disc carried by journaled in the respective sleeves, each of said spindles having a pinion meshing with the portion of other diameter of the drive gear and a control disc on each of said spindles disposed adjacent the control disc of its journal sleeve whereby there is'provided two associate pairs of control discs and the respective discs of each pair are driven at differential rates.

14. A control mechanism for the'movable carriage of a machine tool which has a shaft rotatable in synchronism with the movement of the carriage, said control mechanism including a support mounted on the carriage, a master gear journaled in the support having a pair of drive portions of unequal diameter, driving connections between said shaft and the gear, a pair of sleeves journaled in the support, each having a pinion portion meshing with a portion of the gear of one diameter, a control disc carried by and individual to each of said sleeves, spindles'journaled in the respective sleeves, each of said'spindles having a pinion meshing with the portion of other diameter of the drivegear and a control disc on each of said spindles disposed adjacent the control disc of its journal sleeve whereby there is provided two associate pairs of control discs and the respective discs of each pair are driven at difierential rates, trip levers individual to the respective pairs of discs carried by the support for oscillation relative thereto, and a spring coupling the levers for yieldingly holding the same against oscillatory movement.

15. A control mechanism for the movable cara riage of a machine tool which has a shaft rotatable in synchronism with the movement of the carriage, said control mechanism including a support mounted on the carriage, a master gear journaled in the support having a pair of drive portions of unequal diameter, driving connections between said shaft and the gear, a pair of sleeves journaled in the support, each having a pinion portion meshing with a portion of the gear of one diameter, a control disc carried by and individual to each of said sleeves, spindles journaled in the respective sleeves, each of said spindles having a pinion meshing with the portion of other diameter of the drive gear and a control disc on each of said spindles disposed adjacent the control disc of its journal sleeve whereby there is provided two associate pairs of control discs and the respective discs of each pair are driven at diiferential rates, trip levers individual to the respective pairs of discs carried by the support for oscillation relative thereto, and a spring coupling the levers for yieldingly holding the same against oscillatory movement, each of said levers having a dog operable abutment portion, and dogs individual to the discs of each pair having a path of movement clearing said abutment, said dogs having cooperating portions for effecting projection of one of the dogs into abutment engaging position when the difierential movement of the discs effects interengagement of the dogs.

16. A control mechanism for the movable carriage of a machine tool which has a shaft rotatable in synchronism with the movement of the carriage, said control mechanism including a support mounted on the carriage, a master gear tions between said shaft and the gear, a pair of sleeves journaled in the support, each having a pinion portion meshing with a portionof the gear of one diameter, a control disc carried by and individual to each of said sleeves, spindles journaled in the respective sleeves, each of said spindles having a pinion meshing with the portion of other diameter of the drive gear and a control disc on each of said spindles disposed adjacent the control disc of its journal sleeve whereby there is provided two associate pairs of control discs and the respective discs of each pair are driven at difierential rates, trip levers individual to the respective pairs of discs carried by the support for oscillation relativethereto, and a spring coupling the levers for yieldingly holding the same against oscillatory movement, each of said levers having a dog operable abutment portion, dog's individual to the discs of each pair having a path of movement clearing said abutment, said dogs having cooperating portions for effecting projection of one of the dogs into abutment engaging position when the differential movement of the discs effects interengagement of th dogs, and means yieldingly mounting said abutments on said trips whereby said abutments may be withdrawn out of the path of movement of displaced trip dogs.

17. Control means fora machine tool of the type embodying a support member, a second member mounted on the support member for movement relative thereto, and driving means for effecting relative movement of said members, said control means including a first dog carrier and a second dog carrier mounted on one of said members for movement relative thereto, a projectable trip dog mounted on one of the carriers for movement relative to its carrier, a trip dog carried by the other of said carriers, said carriers being movably supported in juxtapositioned relation to effect interengagement of the dogs upon relative movement of the carriers, said latter trip dog having a portion reacting on the projectable dog upon interengagement of the dogs to :move the projectable trip dog with respect to its carrier, means for effecting movement of one of said dog carriers at a rate in synchronism with the rate of movement of the movable member of the machine, means for moving the other dog carrier at a, different rate than the rate of movement of its juxtapositioned carrier to effect interengagement of the dogs, and a controller for the driving means for said second member of the machine tool coupled with said driving means, said controller having a trip portion positioned adjacent the carrier for the projectable trip dog and engageable by said dog when the latter is projected with respect to its carrier.

18. Control means for a machine tool of the type embodying a support member, a second member mounted on the support member for movement relative thereto, and driving means for effecting relative movement of said members, said control means including a rack carried by one of said members, a shaft carried by the other of said members, a pinion on the shaft meshing with the rack for synchronizing the rate of rotationof the shaft and the rate of movement of the movable member upon relative movement of the members, and control means for the relative movement of said members including a master driver coupled to said shaft for rotation thereby, a pair of control dog carriers movably supported by the shaft supporting member, connections between the master driver and said carriers for efiecting movement of the carriers at relatively different rates, a projectable dog mounted on one of the carriers, an actuating dog mounted on the other of said carriers in position to engage and actuate the projectable dog during movement of the carriers at said relatively different rates, and a control trip coupled with the driving means for the movable member for determining the operative effect of said driving means, said trip having a portion supported by the machine tool in position for engagement by the projectable dog when in itsprojected position.

19. Control means for the translatable element 7 of a machine tool, comprising a driving means 7 for the element, a pair of dog carriers mounted on the machine tool, means for driving said carriers in prescribed paths at different rates to effect movement of the carriers relative to the tool and relative to each other, a projectable the projectable trip dog carrier in position for engagement and actuation by carrier effected movement of the projectable dog when projected.

20. In a machine tool having a traversing table and drive therefor, a trip mechanism to modify the table drive including a dog operated member, a dog carrier mechanism including two dog carrier members rotated in timed relation to the table but at diflerent rates, a first dog positionable on the first carrier member with a member movable between two positions one of which permits it to engage the said dog operated member during rotation of its carrier, a second positionable dog on the second dog carrier member to engage the movable member of the first dog and move. it into position to operate the dog operated member of the trip mechanism.

ALBERT H. DALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,609,217 Stoner Nov. 30, 1926 1,968,255 Lewis et al. July 31, 1934 2,170,494 Ernst et a1 Aug. 22, 1939 2,255,583 Holland Sept. 9, 1941 2,327,486 Alvord Aug. 24,1943 2,561,936 McFerren July 24, 1951 

